Failure of homologous synapsis and sex-specific reproduction problems

The prophase of meiosis I ensures the correct segregation of chromosomes to each daughter cell. This includes the pairing, synapsis, and recombination of homologous chromosomes. A subset of chromosomal abnormalities, including translocation and inversion, disturbs these processes, resulting in the failure to complete synapsis. This activates the meiotic pachytene checkpoint, and the gametes are fated to undergo cell cycle arrest and subsequent apoptosis. Spermatogenic cells appear to be more vulnerable to the pachytene checkpoint, and male carriers of chromosomal abnormalities are more susceptible to infertility. In contrast, oocytes tend to bypass the checkpoint and instead generate other problems, such as chromosome imbalance that often leads to recurrent pregnancy loss in female carriers. Recent advances in genetic manipulation technologies have increased our knowledge about the pachytene checkpoint and surveillance systems that detect chromosomal synapsis. This review focuses on the consequences of synapsis failure in humans and provides an overview of the mechanisms involved. We also discuss the sexual dimorphism of the involved pathways that leads to the differences in reproductive outcomes between males and females

DNA secondary structure is influenced by genetic variation and alters susceptibility to de novo translocation

<p>Abstract</p> <p><b>Background</b></p> <p>Cumulative evidence suggests that DNA secondary structures impact DNA replication, transcription and genomic rearrangements. One of the best studied examples is the recurrent constitutional t(11;22) in humans that is mediated by potentially cruciform-forming sequences at the breakpoints, palindromic AT-rich repeats (PATRRs). We previously demonstrated that polymorphisms of PATRR sequences affect the frequency of <it>de novo </it>t(11;22)s in sperm samples from normal healthy males. These studies were designed to determine whether PATRR polymorphisms affect DNA secondary structure, thus leading to variation in translocation frequency.</p> <p><b>Methods</b></p> <p>We studied the potential for DNA cruciform formation for several PATRR11 polymorphic alleles using mobility shift analysis in gel electrophoresis as well as by direct visualization of the DNA by atomic force microscopy. The structural data for various alleles were compared with the frequency of <it>de novo </it>t(11;22)s the allele produced.</p> <p><b>Results</b></p> <p>The data indicate that the propensity for DNA cruciform structure of each polymorphic allele correlates with the frequency of <it>de novo </it>t(11;22)s produced (r = 0.77, <it>P </it>= 0.01).</p> <p><b>Conclusions</b></p> <p>Although indirect, our results strongly suggest that the PATRR adopts unstable cruciform structures during spermatogenesis that act as translocation hotspots in humans.</p

Expression of myogenin, MyoD and MHC isoforms in regenerating skeletal muscle.

骨格筋再生過程におけるミオシン重鎖(MHC)アイソフォーム発現とmyogenin，MyoDタンパクの発現様式との関連性を検討するために，塩酸ブピバカインを用いてマウスヒラメ筋損傷モデルを作成し，損傷筋の再生過程を組織形態学的に確認すると同時に，再生各段階におけるMHCアイソフォームと，myogeninおよびMyoDタンパク発現を経時的に検索した．本研究における筋損傷は塩酸ブピバカインをマウス(C57BL/10SnSlc)のヒラメ筋に注入することで作成した．組織学的には，塩酸ブピバカイン投与後3日目で筋線維はほとんど消失し，処置後6日目で中心核を有する再生筋線維がかなり出現し，処置後28日目では対照群のものと同程度まで回復した．生化学的分析では，対照群ヒラメ筋はMHCⅠ(34．3±1．7%)とMHCⅡa(65．7±1．7%)で構成されていた．実験群ヒラメ筋ではMHCⅠは処置後14日目まで減少し，その後増加傾向を示し，処置後90日目では36．3±2．9%となった．また，正常ヒラメ筋では検出されない速筋型MHC(MHC Ⅱd，MHC Ⅱb)が処置後3日目から28日目まで検出された．Western blotを用いた分析では，myogeninタンパク正常ヒラメ筋（遅筋）で検出された一方，前脛骨筋（速筋）においては検出できなかった．実験群ヒラメ筋では，myogeninは対照群と比較して処置後３日目より増加し（3．1±0．5），処置後６日目でピークに達した（5．8±0．8）．それからmyogeninタンパクは徐々に減少していったが，処置後90日目においてもなお対照群ヒラメ筋の1．8倍の発現を維持し続けた．一方，MyoDタンパクは正常前脛骨筋において正常ヒラメ筋の3．3倍の発現が認められた．MyoDは処置後３日目で対照群ヒラメ筋と比較して5．4倍になりピークに達した．その後は徐々に減少し始めた．しかし処置後90日目においても2．2倍の発現があった．これらのことから筋の再生過程においては速筋タイプの筋細胞が出現するmyogeninとMyoDは衛星細胞の分化と筋の再生に密接に関係していることが示唆された．To investigate the precise mechanism of skeletal muscle cell regeneration, the changing pattern ofmyosin heavy chain(MHC)isoforms during the regenerating process was observed with relation to theactivation of myogenin and MyoD. In addition, histopathological observation of the damaged muscles wasperformed throughout the experiment.In this study, muscle damage was induced by intramuscular injection of bupivacaine hydrochloride in thesoleus muscle of mice (C57BL/10SnSc). In the light microscopic observation, muscle cells had almost disappeared at 3 days after bupivacainetreatment with severe inflammatory cell infiltration. At 6 days after treatment, a considerable number ofregenerating muscle cells containing centrally located nuclei appeared in the damaged soleus muscle. At28 days, these regenerating muscle cells showed almost the same appearance as the control muscle cellscontaining subsarcolemmal nuclei, although a small number of muscle cells with central nuclei were stillrecognized.In the biochemical analysis, control soleus muscles contained only MHC I (34.3±1.7 %)and MHC IIa(65.7±1.7 %). In the damaged muscles, MHC I was decreased toward 14 days after treatment, and thengradually increased. At 90 days, the contents of MHC I was finally recovered to 36.3±2.9 %.0 In addition,MHC IId and MHC IIb appeared in the damaged muscle from 3 to 28 days after treatment. However, theyhad disappeared at 90 days.Using western blot analysis, myogenin protein was recognized in the control soleus muscles (slow typemuscle), while the myogenin could not be found in the first type muscle of the anterior tibial muscle. Themyogenin contents increased to about three fold (3.1±0.5)at 3 days after treatment compared withthose of control muscles and reached the maximum level (5.8±0.8)at 6 days after treatment. Then, myogenin contents gradually decreased,although they still remained high (1.8 times)at the end of experiment (90 days after treatment). Incontrast to the myogenin protein, a high level (3.3 times)of MyoD protein was detected in the anteriortibial muscle compared with that of control soleus muscles. In the damaged soleus muscles, MyoDcontents reached a maximum level (5.4 times)at 3 days after treatment compared with that of controlsoleus muscles, and then gradually decreased toward the end of experiment. However, MyoD protein stillremained 2.2 times compared with that of control soleus muscles. These findings described above indicate that, 1)a property of fast type muscle cells appeared in theregenerating muscle cells during the regenerating process, and 2)myogenin and MyoD are closelyrelated to the differentiation of the satellite cells and regeneration of the skeletal muscle cells

The role of astrocytes during repair of cerebral infarction in mdx mice

様々な大きさのジストロフィンアイソフォーム(427kDa, 260kDa, 140kDa, 116kDa, 71-75kDa)が広く体内に存在していることはよく知られている.中枢神経系においては71-75kDaのDp71が著明に多く,毛細血管の内皮の基底膜に接しているアストロサイトの細胞質に局在することが報告されている.しかしながらDp71の機能についてはよくわかっていないことが多い.そこで今回,脳組織におけるDp71の役割を調べるために,コントロールマウス(wild-typeマウス)およびデュシャンヌ型筋ジストロフィーモデル動物であるmdxマウスを用いて実験的脳梗塞を作成し,その治癒過程を形態学的に観察した.また,GFAPおよびDp71に関して生化学的に分析をおこなった.HE染色およびGFAP免疫組織学的染色の結果から,形態学的にはmdxマウスとコントロールマウスの脳に違いは認められなかった.しかしながら,mdxマウスの脳において,Dp71の発現量がコントロールマウスよりも少ないことがわかった.またmdxマウスにおいて,脳梗塞の修復過程におけるアストロサイトの反応がコントロールマウスよりも弱いことがわかった.これらの結果から,mdxマウスの脳において,アストロサイトの機能,アストロサイトの血管新生に関わる機能の障害されていることが示唆された.It is now well known that dystrophin isoforms (427kDa, 260kDa, 140kDa, 116kDa, 71-75kDa) are widely distributed throughout our body. In the central nervous system a considerable amount of Dp71 (71-75kDa) is found in the perivascular cytoplasm of the astrocytes. However, the function of this dystrophin is still unknown. To investigate the role of Dp71 in the brain tissue, cerebral infarction was induced in the control (wide-type) mouse and mdx mouse which is known as an animal model of human muscle dystrophy (Duchenne type), and morphological changes of the infarcted area were observed during repair of the infarction. In addition, biochemical analysis of GFAP and Dp71 was carried out in the brain of the control and mdx mouse. In our present study, there were no differences in brain morphology between mdx and control mouse as revealed in H-E stain and GFAP immunohistochemistry. However, the Dp71 were smaller in quantity in the brain of the mdx mouse than that of the control mouse. The reaction of astrocytes during repair of serebral infarction was distinctly delayed in the mdx mouse compared with that of the control mouse. These findings suggest that the astrocytes in the brain of the mdx mouse are functionally impaired including perivascular cytoplasmic processes with relation to neo-vascularization

Efficacy of Brazilian Propolis against Herpes Simplex Virus Type 1 Infection in Mice and Their Modes of Antiherpetic Efficacies

Ethanol extracts (AF-06, 07, and 08, 10 mg/kg) of Brazilian propolis were administered orally to cutaneously herpes simplex virus type 1 (HSV-1)-infected mice three times daily on days 0 to 6 after infection to evaluate their efficacies against HSV-1 infection and significantly limited development of herpetic skin lesions. AF-07 and 08 significantly reduced virus titers in brain and/or skin on day 4 without toxicity, but AF-08 had no anti-HSV-1 activity in vitro. AF-06 and 08 significantly enhanced delayed-type hypersensitivity (DTH) to inactivated HSV-1 antigen in infected mice. Oral AF-08-administration significantly augmented interferon (IFN)-γ production by HSV-1 antigen from splenocytes of HSV-1-infected mice, while direct exposure of splenocytes of infected mice to AF-06 significantly elevated IFN-γ production in vitro. Thus, AF-08 might have components that are active in vivo even after oral administration and those of AF-06 might be active only in vitro. Because DTH is a major host defense for intradermal HSV-1 infection, augmentation of DTH response by AF-06 or 08, directly or indirectly, respectively, may contribute to their efficacies against HSV-1 infection. In addition, AF-06 and 07 possibly contain anti-HSV-1 components contributing to their efficacies. Such biological activities of Brazilian propolis may be useful to analyze its pharmacological actions

Function of skeletal muscle sarcoplasmic reticulum and expression of sarcoplasmic reticulum Ca2+-ATPase in right congestive heart failure rats

右心不全に伴って,速筋および遅筋の筋小胞体Ca2+取り込み能が減少するという仮説を検証した.右心不全は,モノクロタリン(30 ㎎/㎏)を投与することにより引き起こし,投与後4週で,長指伸筋およびヒラメ筋を両後肢から採取した.筋の疲労耐性は,連続的な強縮刺激を行うことにより測定した.長指伸筋では刺激開始1分後,ヒラメ筋では4分後の張力を測定し,初期値に対するそれらの割合を疲労の指標とした.長指伸筋およびヒラメ筋の疲労耐性は,右心不全群で有意に低下した.筋小胞体Ca2+取り込み速度は,Indo-Ⅰを付加したホモジネートで測定した.その結果,Ca2+取り込み速度は,長指伸筋で25.4%(p<0.01),ヒラメ筋で30.4%(p<0.05)低下した.このCa2+取り込み速度の低下は,筋小胞体Ca2+-ATPaseタンパク量の低下と一致した.筋小胞体Ca2+取り込み能の低下は,筋張力の低下を引き起こし,このCa2+ handlingの低下は,少なくとも右心不全による運動耐容能の低下の一因であろう.In this study, we investigated the hypothesis that right congestive heart failure (CHF) would impair sarcoplasmic reticulum (SR) Ca2+ uptake in skeletal fast- and slow-twitch muscles. To induce CHF, the rats were injected with monocrotalin (30 ㎎/㎏). After 4 weeks of injection, extensor digitorum longus (EDL) and soleus (SOL) muscles were sampled from both hind limbs. Muscle fatigue resistance was measured in vitro as the relative decline in force production of tetanic contraction induced by electrical stimulation over 1 and 4 min in EDL and SOL, respectively. Evaluation of fatigue characteristics showed that CHF significantly reduced fatigue resistance in both muscles under study.SR Ca2+uptake rate wasmeasured in vitro with Indo-I on muscle homogenates. As hypothesized, Ca2+uptake rate was decreasedby 25.4%(P < 0.01) and 30.4%(P < 0.05) in EDL and SOL, respectively. This decline in Ca22+uptake ratewas accompanied by an immunochemically determined decrease in SR Ca2+-ATPase protein. Taking intoaccount previous findings that the depressed SR Ca2+uptake leads to the reduce in muscle forceproduction, these results suggest that impaired SR Ca2+handling capacity in skeletal muscle may accountat least partly for deteriorations in exercise tolerance resulting from right CHF

Dietary Supplementation with Monosodium Glutamate Suppresses Chemotherapy-Induced Downregulation of the T1R3 Taste Receptor Subunit in Head and Neck Cancer Patients

(Background) We investigated the effect of dietary supplementation with monosodium glutamate (MSG) on chemotherapy-induced downregulation of the T1R3 taste receptor subunit expression in the tongue of patients with advanced head and neck cancer. (Methods) Patients undergoing two rounds of chemoradiotherapy were randomly allocated to a control or intervention group (dietary supplementation with MSG at 2.7 g/day during the second round of chemotherapy). The relative expression of T1R3, a subunit of both umami and sweet taste receptors, in the tongue was assessed by quantitative polymerase chain reaction analysis. Dysgeusia was assessed with a visual analog scale and daily energy intake was evaluated. (Results) T1R3 expression levels in the tongue, taste sensitivity, and daily energy intake were significantly reduced after the first round of chemotherapy compared with before treatment. Furthermore, these parameters significantly decreased after the second round of chemotherapy, but the extent of decrease was significantly attenuated in the MSG group compared with the control group. (Conclusions) MSG supplementation suppresses chemotherapy-induced dysgeusia, possibly due to the inhibition of the T1R3-containing taste receptor downregulation in the tongue, thereby increasing energy intake in patients with advanced head and neck cancer

In vitroNeo-Genesis of Tendon/Ligament-Like Tissue by Combination of Mohawk and a Three-Dimensional Cyclic Mechanical Stretch Culture System

Tendons and ligaments are pivotal connective tissues that tightly connect muscle and bone. In this study, we developed a novel approach to generate tendon/ligament-like tissues with a hierarchical structure, by introducing the tendon/ligament-specific transcription factor Mohawk (MKX) into the mesenchymal stem cell (MSC) line C3H10T1/2 cells, and by applying an improved three-dimensional (3D) cyclic mechanical stretch culture system. In our developed protocol, a combination of stableMkxexpression and cyclic mechanical stretch synergistically affects the structural tendon/ligament-like tissue generation and tendon related gene expression. In a histological analysis of these tendon/ligament-like tissues, an organized extracellular matrix (ECM), containing collagen type III and elastin, was observed. Moreover, we confirmed thatMkxexpression and cyclic mechanical stretch, induced the alignment of structural collagen fibril bundles that were deposited in a fibripositor-like manner during the generation of our tendon/ligament-like tissues. Our findings provide new insights for the tendon/ligament biomaterial fields

monosodium glutamate increases T1R3 expression

We previously showed that chemotherapy-induced dysgeusia was associated with lingual taste receptor gene expression, and monosodium glutamate (MSG) improved dysgeusia by upregulating taste 1 receptor 3 (T1R3) gene expression. In recent years, decreased taste sensitivity has also been reported in some young people, and these are partly due to their disordered eating habits. From these background, we investigated the effects of MSG supplementation on taste receptor expression and dietary intake in healthy females. Fifteen young healthy volunteers were enrolled for the present crossover study and divided in two groups (dietary supplementation with MSG at 2.7 g / day or 0.27 g / day). The relative expression of T1R3, a subunit of both umami and sweet taste receptors, in the tongue was assessed by quantitative PCR analysis. Food intake was assessed by food frequency questionnaire (FFQg), and body composition was measured using Omron HBF-701. T1R3 expression levels in the tongue and taste sensitivity increased significantly in participants who consumed 10 g of MSG daily. Furthermore, protein, fat, and carbohydrate (PFC) balance and salt and sugar intake improved by MSG supplementation. In conclusion, MSG supplementation increased T1R3 expression in the tongue and improved dietary balance